import React,{Component} from 'react'
//引入store,用于获取redux中保存的状态
import store from '../../redux/store'

export default class Count extends Component{

  // 单个组件使用redux，若组件多，则去index.js使用
  // componentDidMount(){
  //   //检测redux中状态的改变，只要变化就调用render
  //   store.subscribe(()=>{
  //     this.setState({})   //欺骗render。使其调用，实际什么都没修改，仅让render起更新作用
  //   })
  // }

  //加
  increment = ()=>{
    const {value} = this.selectNumber
    // 告诉store，需要传递的参数
    store.dispatch({type:'increment',data:value*1})
  }
  //减
  decrement = ()=>{
    const {value} = this.selectNumber
    store.dispatch({type:'decrement',data:value*1})
  }
  //奇数再加
  incrementIfOdd = ()=>{
    const {value} = this.selectNumber
    const count = store.getState()      //这里获取的是数值（store里定义的），不需要解构赋值使用{}
    if(count%2 !== 0){
      store.dispatch({type:'increment',data:value*1})
    }
  }
  //异步加
  incrementAsync = ()=>{
    const {value} = this.selectNumber
    setTimeout(()=>{
      store.dispatch({type:'increment',data:value*1})
    },500)
  }

  render(){
    return (
      <div>
        <h1>当前求和为：{store.getState()}</h1>
        <select ref={c => this.selectNumber = c}>
          <option value="1">1</option>
          <option value="2">2</option>
          <option value="3">3</option>
        </select><br />
        <button onClick={this.increment}>+</button>&nbsp;
        <button onClick={this.decrement}>-</button>&nbsp;
        <button onClick={this.incrementIfOdd}>当前求和为奇数再加</button>&nbsp;
        <button onClick={this.incrementAsync}>异步加</button>
      </div>
    )
  }
}